1. Field of the Invention
This invention pertains to rotary actuators of the type in which reciprocation of a piston causes simultaneous rotation through interengaging helical splines within the cylinder.
2. Description of the Prior Art
Helical rotary actuators are known. Examples are shown in U.S. Pat. Nos. 3,213,923; 3,453,938; 2,283,185; 2,117,225; 3,133,476; 3,141,387; 2,429,863 and 3,319,925. All of these known actuators, however, are expensive to manufacture greatly reducing their competitive usefulness relative to other types of rotary actuators.
In rotary actuators of the type having a hydraulically or pneumatically powered reciprocating piston in particular, and in other linear devices using a reciprocating piston in general, it is frequently desirable to adjust the limit of stroke of the piston to adjust the rotational or linear end position of the output member. In an embodiment of this invention the adjustment of the limit of piston stroke is obtained by threadably adjusting an end cap of the cylinder within the cylinder. When rotational adjustment of a cylinder end cap is thus encouraged, it frequently becomes unthreaded for such adjustment beyond the number of turns recommended by the manufacturer and the pressure in the cylinder over stresses the few threads left holding the end cap, causing the end cap to be blown off the cylinder.